New research indicates 80 percent of all species on Earth were wiped out

By Mitchell Byars Camera Staff Writer

Posted:
03/27/2013 04:38:11 PM MDT

Updated:
03/27/2013 04:46:39 PM MDT

A new CU-Boulder study shows that an asteroid believed to have smacked Earth some 66 million years ago likely caused a global firestorm that led to extensive plant and animal extinctions. (Illustration courtesy NASA / JPL)

A University of Colorado study published this week indicates that the asteroid that hit Earth 66 million years ago and wiped out the dinosaurs likely also triggered a global firestorm and led to the extinction of 80 percent of all species of life on the planet.

The study was led by Douglas Robertson of CU's Cooperative Institute for Research in Environmental Sciences, and used models to show that the impact of an asteroid the size of Manhattan Island in Mexico's Yucatan Peninsula vaporized a large amount of rock that was sent into the atmosphere.

As the vaporized rock condensed into sand-size grains and began to fall back to Earth, the particles retained about 20 percent of the kinetic energy from the impact and heated up the atmosphere to about 2,700 degrees Fahrenheit.

"It was about the temperature of the broiler elements in your oven," Robertson said Wednesday. "If you stick your hand in the oven while it's on broil, the whole sky would be that temperature for a couple of hours."

The initial impact generated 100 million megatons of energy, and 20 million megatons of that radiated back down to Earth and sparked fires across the globe. One megaton is the equivalent of a hydrogen bomb or 80 Hiroshima-type nuclear bombs, and the firestorm was equivalent to one of those hydrogen bombs falling every 6 kilometers across the planet within hours.

The resulting heat burned every twig and branch on the ground and completely wiped out 80 percent of the species of life on Earth, according to the study. Robertson said ash found in New Zealand and Europe can account for the entire biomass burned up during the firestorms. The only things that survived were either underground or underwater.

"What is it that was underground or underwater?" Robertson said. "Mammals, lizards, turtles, burrowing birds. It's an exact match for what is observed to have made it through the extinction."

But even life underground and in the water barely survived the firestorm, and a very small amount of life was left to propagate and repopulate the planet.

"It was a small fraction of the population that existed before," Robertson said. "There was nothing the next morning larger than a squirrel except in the water."

Robertson said the study helps to lend a greater understanding of the effects of large impacts on Earth.

"It will contribute to our understanding of the nature of asteroid impacts," he said.

Robertson pointed out that the meteor that struck Russia last month and injured hundreds was tiny compared to the asteroid that struck Mexico.

"That was a little tiny thing compared to this," Robertson said. "The one in Russia was the size of a small school bus. The one we studied was the size of Mount Everest."

Thankfully, it doesn't appear Earth will be reliving anything similar in the near future.

"There are other asteroids out there, but none are known to be in a collision course with Earth, which is a good thing," he said. "You certainly don't want to be around when that happens."

Of course, Robertson added that, in the distant future, it is entirely possible something lurking beyond Saturn could make even the fiery doom the Earth went through 66 million years ago look tame.

"There are all sort of interesting things in the universe that could make this look like a tiny firecracker," he said.

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